The progression of passenger vehicles is progressing, and regulations are continually being revised, resulting in a decrease in car exhaust emissions. The European Commission has revised the RDE test procedure to include exhaust emissions during a cold start, as part of package 3. The article carried out simulations using COPERT software, which uses tests based on WLTP, assuming ambient temperatures from -10◦C to +20◦C, at intervals of 5◦C. This paper aims to present the results of mathematically modelling the influence of ambient temperature on the cold-start emissions of carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOC), hydrocarbons (treated as Volatile organic compounds - VOC), total particulate matter (TSP) and particle number (PN) in passenger cars and light-duty vehicles. The modelling results show that a change in ambient temperature significantly affects carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOC), hydrocarbons (treated as Volatile organic compounds - VOC), total particulate matter (TSP) and particle number (PN) in cold-start emissions.